Conrad Black, the dethroned press baron on trial in Chicago on fraud and racketeering charges, won’t be seeing his turncoat deputy David Radler back on the witness stand.

Black’s lawyers had sought to have Radler – the government’s star witness – return for more questioning in hopes they could show he lied to the jury during his testimony, but the judge presiding over the case shot down the request yesterday.

The lawyers wanted a chance to re-quiz Radler about his “professed ignorance” about the cushy sentencing guidelines in his native Canada.

While on the stand last month Radler, who copped a plea with prosecutors in exchange for a light sentence near his home in Vancouver, told the jury he had no idea his 29-month prison term could see him out on parole in as little as six months.

After Radler left the witness box, Black’s lawyers called a leading parole expert in Canada in hopes he might testify about the country’s lax sentencing rules.

They discovered Radler had hired the lawyer in November 2004, a month before he reached a deal to rat out his boss.

Black’s legal eagles argued that it shows why he agreed to testify for the government and also that he lied to the jury when claiming ignorance about Canadian parole rules.

Judge Amy St. Eve told the lawyers yesterday that she didn’t buy their argument because they were seeking to impeach Radler on matters that they “could have discovered much earlier.”